Process for producing incandescent mantles.



UNITED sTAT s ear r si es.

PROCESS FOR PRODUCING INCANDESCENT MANTLES.

Specification of Letters Patent.

Patented July 20, 1909.

Application filed March 8, 1907. Serial No..361.405.

To all w/zom it may concern.

Be it known that I, Gnone Brntiuxx, a subject of the King of Prussia, and resident of 4 Arndtstrassc, Grossliichlerl'clde, near Berlin, Kingdom of Prussia, Germany, have invented an improved Process for Producing Incandescent Idantles, of which the following is a specification.

As is well known the incandescent light trade has in addition to finished and burnedoll' incandescent mantles to deal, with large quantities of impregnated but not burned-oii' mantles. It is very essential that such mantles should be non-hygroscopic, inasmuch as mantles with but a trace of moisture burn oil' very badly. In View of this it has been the practice to pack mantles intended for seatransport in zinc boXes well-soldered all around, but this preparation has )rovcd to be no'safeguard against the dillicult-ies mentioned, especially in countries with a very damp climate. Inasmuch as the customary salts, especially the nitrates of rare earths, such as thorium and cerium are used for the impregnation of the mantles, substances which are all very hygroscopic, it is quite.

natural that these qualities are imparted to themantle togetl'icr with the defect caused by the acid reJ-action of those salts which aliects the strength of the fabric, especially during a long storage of the mantles. This defect of destroying the strength of the fabric in the course of. time is intensified in mantles made of artificial cellulose or what is called artificial ilk, to such an extent that it renders such mantles a short time after their impregnation and drying, perl'ectly brittle, so that they Wlll tear when an attempt is made to strip them from the form. Such fabrics in such condi ion cannot be burned ell as they will fly asunder in small particles when burned. The latter defeet is not observed in mantles made of nat- ,ural cellulose such as cotton, ramie fiber and the like, and furthermore in such mantles the fibers are not weakened to any considerable extent. The reason for this may be found in the smaller size of the molecules consti tuting the artificial silk, inasmuch as such silk is an oxidized or hydro-oxidized cellu lose substance whose reactions toward nitrates differ from those of natural cellulose.

N ow-I have found that all the defects mentioned, which are particularly noticeable where artificialsilk is used, can be avoided by reducing the acidity of the fluids used for impregnation of the mantles. in order to accomplish tins, several means and ways can be employed. 'i he addition ol ammonia to the usual solution consisting ol' nit-rates oi a thorium or cerium will accomplish the purpose best, but instead ol' ammonia other volatile bases may be employed. Furthermore hydroxid of thorium ('l"l1(()lI),), hy droxid of cerium (Ce (()li) hydroxid of beryllium (Be(()ll),) or hydroxid lalrlI11i1'ii um (Al(()ll).,) may be used to advantage, or they can ganic non-precipitating salts. Any one of these above named chemicals is capable oi reducing the acidity ol the commonly used solution of nitrates oi thorium or cerium, il added to same in proper proportion. The limit point up to which the additions may be safely carried, is the co-called point of saturation. This limit is reached at the moment l when pr -*cipitations settle at the bottom of the solution which do not dissolve even if the solution be well shaken. 'lhus as long as the precipitations caused by the added chemicals in the fluid dissolve again, so that the solu tion remains clear or becomes clear again after being well shaken, the point of saturation has not been reached; but as soon as the precipitation leaves some sediment in the fluid which does not dissolve again, the solution has absorbed all the addition of which it is :apable, in other Words, the fluid is saturated and no more chemicals must be added.

In case ammonia is selected as acidity reducer, it is to be carefully added to the solution and hydrates of the rare earth salts are precipitated therein, which readily redissolve 1f the whole solution is Well shaken. Nr'hen therefore, a sediment of these precipitations remains undissolved in the solution after being shaken, the saturation point of the solution in regard to the. taking of additional ammonia is reached. Should, however, a

slight precipitation remain, it can easily be removed by filtering the solution. If thorium-oi rid, or the ashes of incandescent mantles, are chosen as the reducers of the acidity of the solution, they can be added in excess. T he surplus remaining non-dissolved in the fluid is removed from same by filtration. Another method of adding such oxid would be to place them in layers upon filter and then pour the solution over them, thus making the solution slowly run through the layer.

I claim i 1. Process for the impregnation of incan-' be used in the form of their or descent mantles consisting in dissolving a salt of an illuminating rare earth metal, adding to said solution a substaneecapable of reducing the acidity of said solution shaking saidsolution in order to redissolve the precipitate, repeating the addition of the substance for reducing the acidity and shaking until the precipitate formed can no longer be dissolved and (a ipping the mantle fabric in the impregnating bath so formed.

' 2. Process for the impregnation of incandescent mantles consisting in dissolving a salt of an illuminating rare earth metal, adding ammonia thereto, shaking the solution 15-, till the precipitate formed is dissolved repeating said addition and said shaking 'till saturation of the solution and dipping the mantle fabric in the basic solution formed in this way.

-3. As an article ofmanufacture a mantle comprising a fabric of artificial silk im regnated with a saturated solution of a baslc recipitate from a solution of a salt of an illuminating rare earth metal.

In witness whereof I have hereunto set my hand in the presence of two Witnesses.

GEORG BUHLMANN. Witnesses:

HENRY HAsPER, WOLDEMAR HAUPT. 

